A product requiring air-tightness like common beverages or medical supplies is packaged in a container and, then for the purpose of ensuring the air-tightness, the entrance of the container is sealed with a seal made of a synthetic resin in the form of a film (hereafter, referred to as a “seal”). The seal seals the entrance of a container which packages the beverage or medical supplies, etc., and is made of various materials like plastic or glass, so that products like liquefied or damp material or dry powder can be prevented from leaking out of the container or from being absorbed by the outside air.
However, since the entrance of the container and the seal are completely adhered to each other, the sealing is effectively done. When the contents of the container are intended to be extracted, the seal is required to be peeled. Here, since there is no gap between the container and the seal, it is difficult to peel the seal. Also, in some cases, the gap is created by means of a hand or a tool such as scissors. Therefore, the hands or tool contacts with the entrance of the container, so that sanitary problems occur.
Therefore, in order to overcome the above-mentioned problems, the conventional technologies have been presented. For one example, as shown in FIG. 6a, proposed was a configuration in which the holding parts are formed at the edge of the seal. However, such a configuration has problems in the manufacturing process and cost, and it is difficult to open the seal due to the small holding part. To overcome this, FIG. 6a shows a small handle is attached to the seal. The structure of FIG. 6b can be shown in the Korean Patent No. 10-0711073 filed and registered by the present inventor. The seal of FIG. 6a has a tap formed on the top surface thereof for easy opening and is easily detached from the container by holding the tap. The Korean Patent No. 10-0711073 discloses a container seal to which the tap has been attached and which includes a surface layer which is located on the top of the seal of the container and is made of a material having no thermal adhesiveness; a thermal adhesive resin layer which is formed by laminating a thermoplastic resin with a suitable thickness on the surface layer; an adhesive layer which is made of a thermoplastic resin or adhesive agent and is adhered under the thermal adhesive resin layer; an intermediate base layer which is adhered to the adhesive layer and is made of aluminum foil or plastic film; and a sealing adhesive layer which is adhered under the intermediate base layer and is adhered to the container made of an adhesive thermoplastic resin or viscous agent. The publication of Korean Patent Application No. 2010-0040286 discloses a seal for food stuff container. The seal is formed by laminating through the coextensive inclusion of a) a plastic top layer; b) a plastic/foaming agent adhesive layer; c) a foam layer; d) a foaming agent/foil adhesive layer; e) metal foil; and f) a thermo-sealing layer. The plastic/foaming agent adhesive agent causes the foaming agent to adhere to the plastic top layer with respect to at least a portion of the opposite side between them. The foaming agent/foil adhesive layer causes the foaming agent to adhere to the foil over the substantially entire area of the opposite side between them by an adhesive strength of at least 8N/12.5 mm measured by a 180° peel test to be described in the detailed description of the invention. When measured by the density measurement method described herein, the measured density has a value within a range between 0.6 and 0.95 ml−1.
However, the seal according to the presented methods still has a complex manufacturing process, a high manufacturing cost, and a high error rate due to the inconvenient work. Therefore, there is a requirement for the improvement of this. In order to satisfy the requirement, the Korean Patent No. 10-1196147 filed by the applicant discloses a seal which has an adhesive surface and a non-adhesive holding part formed on the top thereof for the purpose of easily opening, so that the seal is easily detached from a container by holding the holding part. The seal includes a surface layer which is located on the top of the seal of the container and is made of a material having no thermal adhesiveness; a top layer which is formed by laminating a plastic film with a suitable thickness on the surface layer; an intermediate layer which is formed by laminating the plastic film or polyolefin foaming agent on the aluminum foil; and a sealing adhesive layer which is adhered under the intermediate layer and is adhered to the container made of the adhesive thermoplastic resin or viscous agent. The holding part is formed on the bottom surface of the top layer made of the plastic film and on the aluminum foil layer of the top surface of the intermediate layer formed by laminating the plastic film or polyolefin foaming agent on the aluminum foil.
However, when the container is sealed with the seal configured as described above, the forming agent located in the intermediate layer causes the increase of a high frequency, poor sealing, and curling of a finished product of the seal. As a result, it becomes difficult to perform the sealing process.